Chemical Properties
Pale grey to brown solid
Uses
Used in the manufacturing of dyes, intermediates, synthetic perfumes.
Definition
ChEBI: A naphthol carrying a hydroxy group at position 1.
Hazard
Toxic by ingestion and skin absorption.
Description
Alpha-naphtol, combined with epichlorhydrine and
sodium hydroxide to form alpha-naphtyl glycidyl
ether, caused sensitization in one of three workers in
a chemical plant.
Application
1-Naphthol is a hydroxyl-aromatic compound. It has been used as a prooxidant to analyze its ability to induce hemolysis in a zebrafish G6PD (glucose-6-phosphate dehydrogenase) deficiency model.
Preparation
2-Isopropylnaphthalene can be used to synthesize 1-naphthol by oxidation via the hydroperoxide (Hock synthesis).
Historically 1-naphthol was produced via caustic fusion of naphthalene-1-sulfonic acid, but this was superseded by the I.G. Farbenindustrie process involving hydrolysis of 1-naphthylamine with aqueous 22 % sulfuric acid at 200°C under pressure in a lead-lined autoclave. To obtain a purer product, Union Carbide developed a process based on catalytic oxidation of tetralin to 1-tetralol and 1-tetralone followed by dehydrogenation. The two-stage catalytic process is claimed to give an overall yield of 72% 1-naphthol, with an overall efficiency of 97%.
Reactions
1-Naphthol is reduced by sodium in liquid ammonia to give 5,6,7,8-tetrahydro-1-naphthol; oxidised by NaOCl - FeCl3 or I2-KI to give a purple colour. Phosphorus pentachloride is chlorinated at 150 °C to give 1-chloronaphthalene, thionyl chloride to give 4-chloro-1-naphthol, or Cl2-CH3COOH to give 2,4-dichloro-1-naphthol. Similarly, bromine produces 2,4-dibromo-1-naphthol, a reaction that can be used in quantitative titrations. Its nitration reaction produces a complex mixture. The crude 2,4-dinitro derivative is used as an acidic yellow dye, comparable to picric acid. Sulfonation at 50 °C readily produced 1-naphthol-2,4-disulfonic acid.
General Description
1-Naphthol, a metabolite of carbaryl and naphthanlene. It is formed by spontaneous reaction from (1R, 2S)-Naphthalene epoxide followed to form 1, 4-Dihydroxynaphthalene.
Flammability and Explosibility
Notclassified(100%)
Synthesis
To a 10 mL pressure vessel, aryl halide (1.00 mmol), copper (I) oxide (0.05 mol), ligand (0.05 mol), 3 M sodium hydroxide (2 mL), and organic solvent (2 mL) were added. The reaction mixture was irradiated at 160 °C for 10 min with strong stirring. The reaction mixture was allowed to cool to room temperature. The reaction mixture was filtered through a plug of celite in a fritted filter funnel and washed with ethyl acetate. The product was extracted using 30 mL of ethyl acetate for three times. The organic extract is washed three times with 10 mL water and two times with 10 mL of brine. The combined organic phases were dried over anhydrous MgSO4 and the solvent was removed under reduced pressure to afford 1-naphthol.
Purification Methods
Sublime 1-naphthol, then crystallise it from aqueous MeOH (charcoal), aqueous 25% or 50% EtOH, *C6H6, cyclohexane, heptane, CCl4 or H2O. Dry it over P2O5 in vacuo. The 4-nitrobenzoate has m 143o (from EtOH). [Shizuka et al. J Am Chem Soc 107 7816 1985, Beilstein 8 H 596, 6 IV 4208.]
